Comment by schoen

Maybe a bank of (extremely) huge capacitors that get charged up very quickly, and are then connected to a battery pack to charge it more slowly?

Keeping control of those charges seems like a huge challenge, as they literally contain the electrical energy of a lightning bolt. I guess for physically plausible capacitors you'd also need to step the voltage way down (by six or eight orders of magnitude!?) before it reaches the capacitors. Are there physically-plausible transformers or other devices that could do that?

Or something that somehow captures the lightning as (lots and lots of) mechanical or thermal energy and then gradually converts that back into electricity?